.\" -*- nroff -*-
.\"
.\" copyright (C) 1997 Stephen Williams <steve@icarus.com>
.\"
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.\" manual provided the copyright notice and this permission notice are
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.TH skel 9 "$Date:$" "Linux DDI" "VM Functions"
.\"
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.hlm 0
.na
.\" The name should be formatted this way for apropos to work
.SH NAME
mem_map_reserve, mem_map_unreserve \- Manipulate flags of virtual memory pages.
.\"
.\"
.SH SYNOPSIS
.B #include <linux/mm.h>
.br
.B #include <linux/wrapper.h>
.sp
.BI "#define mem_map_reserve(" page_nr ")"
.br
.BI "#define mem_map_unreserve(" page_nr ")"
.HP
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.ad
.SH DESCRIPTION
These macros cause a page to become reserved/unreserved. A reserved
page is reserved from any further consideration by the linux kernel,
meaning it is not scanned as potentially pageable, or available for
page allocation. The kernel treats reserved pages as memory-mapped
hardware.
.PP
It makes sense for a driver to mark a page reserved, for example, if
the driver supports
.BR mmap "(2)"
with dynamically allocated pages that the target device can access via
DMA.
.SH "RETURN VALUE"
None
.SH AVAILABILITY
Linux 2.0+
.SH "SEE ALSO"
.hlm 0
.na
.BR MAP_NR "(9), " get_free_pages "(9), " mmap "(2)"
.ad
.hlm 1
.SH AUTHOR
Stephen Williams <steve@icarus.com>
.SH BUGS
If a page is marked reserved, a call to
.BR free_page "(9)"
will silenty ignore it. If the page was originally allocated by
get_free_page, you must remember to unmark the page before releasing
it to the system. Otherwise, the page is lost.
